Add support of JSONL and CSV input file formats in CLI tabulate utility

[astanin]

fix#173

New CLI parameters:

--headers HEADERS
where HEADERS can be "firstrow", "keys", "HEADER1,HEADER2,..." (for CSV data), "HEADER1,KEY2:HEADER2,..." (for JSONL data)

--read FILEFORMAT
where FILEFORMAT can be "rsv" (default), "csv", "jsonl"

Deprecated CLI parameter:

• --header

Usage examples:

cat ./examples/people.csv | tabulate -r csv --headers firstrow
id name email "favorite" fruit
---- ------ ----------------- ------------------
1 Alice alice@example.com apple, kiwi
2 Bob bob@example.com banana,
orange,
lychee
3 Carol pear

cat ./examples/people.jsonl | tabulate -r jsonl -f grid --headers 'id:ID,name:First Name,email:Email'
+------+--------------+-------------------+
| ID | First Name | Email |
+======+==============+===================+
| 1 | Alice | alice@example.com |
+------+--------------+-------------------+
| 2 | Bob | bob@example.com |
+------+--------------+-------------------+

[codecov-commenter]

Codecov Report

❌ Patch coverage is 97.11538% with 3 lines in your changes missing coverage. Please review.
✅ Project coverage is 90.18%. Comparing base (2070736) to head (5313627).
⚠️ Report is 8 commits behind head on master.

Files with missing lines	Patch %	Lines
tabulate/__main__.py	0.00%	2 Missing ⚠️
tabulate/__init__.py	0.00%	1 Missing ⚠️

Additional details and impacted files

@@ Coverage Diff @@## master #419 +/- ##
==========================================
+ Coverage 84.43% 90.18% +5.75% 
==========================================
Files 1 3 +2 Lines 906 958 +52 Branches 218 228 +10 ==========================================
+ Hits 765 864 +99 + Misses 107 60 -47 
Partials 34 34 

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